Production of viscous cellulose solutions.



UNITED STATES PATENT OFFICE.

EMILE BRONNEBT, OF NIEDERMORSCHWEILER, GERMANY, ASSIGNOR TO VEREINIG-TE GLANZSTOFF-FABRIKEN-A.-G., ELBERFELD, GERMANY.

PRQDUCTION 0F VISQOUS CELLULOSE SOLUTIONS.

No Drawing.

lutions.

It relates further to a method in which the cellulose solutions are obtained from cellulose in any form.

It relates particularly to a method in which the waste products of the artificial silk industry, say cellulose e. g. are subjected to the action of concentrated phosphoric acid and formic acid. I

It is well known that the hydrates of a certain composition occurring as waste products in the manufacture of artificial silk, when treated in formic acid, form, after some time and under ordinary temperature, without the addition of a condensation medium, and under formation of esters, a technically important solution of cellulose formate in formic acid. Ordinary bleached or mercerized cellulose does not dissolve under these circumstances. Now I have discovered that by using a mixture of formic acid and concentrated phosphoric acid ordinary cellulose can also be brought into solution. Of course also the altered cellulose known as waste products in the artificial silk industry, (for example, the lustersilk (glanzstofi'), viscous-silk, denitrated nitro-silk), pass into solution under these circumstances, possibly with the formation of new acid combinations. In fact, cellulose products of any form (unaltered, altered, Waste, etc.) may be used in carrying out the invention. It is also known that acetic acid and phosphoric acid are suitable for effecting solutions of cellulose. In comparison therewith, the mixture of phosphoric and formic acids possesses not only the advantage of greater economy, but

Specification of Letters Patent.

Application filed February 11, 1911.

Patented Mar. 11, 191a.

Serial No. 608,108.

uniformly melting (so to say) just as the colloid gum arabic changes to a slime in water. There is, therefore, an important technical difference and advance over the application of acetic acid. The higher fatty acids do not behave similarly as assisting solution or preventing decomposition. so that the behavior of the formic acid is to be considered as characteristic.

As an example: Into 1 kilogram of concentrated formic acid (about 99%) mixed with 1 kilogram of concentrated phosphoric acid, there are stirred 200 grams of slightly bleached cotton. After a few hours, With out further stirring, the cellulose yields a syrupy viscous liquid. i

In the above example, if the cotton is replaced by artificial silk waste, in half the time already a syrup colored only slightly yellow is obtained.

The solutions thus prepared are applicable for the manufacture of threads, etc, from which in practice the phosphoric acid can be removed in any suitable manner, such e. g. as washing. The prgfiuct obtained by precipitating the solution and practically after the removal of the phosphoric acid residue, can also be used if desired for the manufacture of noninflammable celluloidlike substances by mixing with camphor or camphor-substitutes such as triphenylphosphate for instance.

Having thus fully set forth my method,

and the manner in which it is to be carried lulose solutions, which consists in forming a signed my name in the presence of two submixture composed of equal parts of concenscribing Witnesses. trated phosphoric acid and formic acid and dissolving therein cellulosic material in EMILE BRONNERT.

amount by Weight, equal to about one- Witnesses:

tenth of the Weight of the acid mixture. HENRY HASPERQ, In Witness whereof, I have hereunto RICHARD GOETZ. 

